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MLS Hematology > Unit 16: Macrocytic anemias > Flashcards

Unit 16: Macrocytic anemias Flashcards

1
Q

What is the main cause of megaloblastic anemia?

A

Impaired DNA synthesis; reduction in the number of cell divisions

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2
Q

When B12 or folate is deficient, the production of what nucleotide is impaired?

A

Thymidine

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3
Q

Which deficiency has more of a direct affect, folate or B12?

A

Folate, in preventing the methylation of dUMP

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4
Q

Which deficiency has more of an indirect affect, folate of B12?

A

B12, preventing the production of THF from 5-methyl THF

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5
Q

If there is no B12, what happens to the inactive folate that needs to be converted?

A

It is stuck in its inactive form, aka the folate trap

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6
Q

Where is 5-methyl THF converted into THF?

A

The cytoplasm

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7
Q

What happens to 5-methyl THF if it is not readily polyglutamated in the cell?

A

It will leak out of the cell, decreasing the intracellular folate

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8
Q

What happens to homocysteine in the case of B12 or folate deficiency?

A

It accumulates because methionine synthase is unable to convert it to methionine without vitamin B12 as a cofactor

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9
Q

What happens to the DNA in the case of a thymidine deficiency?

A

Uracil is incorporated into the DNA strand instead and is then removed in the replicated strand. This causes many single strand breaks

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10
Q

What is the term for abnormal blood cell development?

A

Ineffective hematopoiesis

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11
Q

What happens to most of the early erythroid progenitors and precursors in megaloblastic anemia?

A

They are destroyed when devision is halted via cell lysis or apoptosis

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12
Q

What happens to the abnormal cells that do make it to the peripheral blood stream in megalobastic anemia?

A

They are increased in size, macrocytic

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13
Q

Can RNA synthesis occur without thymidine?

A

Yes, it needs uracil instead

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14
Q

As a result of RNA synthesis occurring and DNA synthesis halting, what happens to the cytoplasm development?

A

Cytoplasm is able to develop normally, in asynchrony with the nuclear development

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15
Q

What is pancytopenia?

A

Ineffective hematopoiesis of all 3 blood cell lineages

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16
Q

What are the general symptoms of anemia?

A

Fatigue, shortness of breath, and weakness

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17
Q

What are some of the neurologic manifestations of B12 deficiency?

A

Memory loss, numbness, tingling, loss of balance

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18
Q

What are some of the neuropsychiatric manifestations of B12 deficiency?

A

Personality changes and psychosis

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19
Q

What are some of the specific manifestations of folate deficiency?

A

Depression, peripheral neuropathy, psychosis and neural tube defects (i.e. spina bifida)

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20
Q

What is the most common cause of folate deficiency?

A

Inadequate intake

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21
Q

What is the most common cause of B12 deficiency?

A

Impaired absorption

22
Q

What are the 5 causes of impaired absorption of B12?

A

Failure to separate, lack of intrinsic factor, malabsorption, inherited factors and competition

23
Q

What is it called to have a loss of epithelial cells on the tongue, resulting in a smooth surface and soreness?

A

Glossitis

24
Q

Which one takes longer to develop symptoms for, B12 deficiency or folate deficiency?

A

B12 - up to a few years, folate - up to a few months (this reflects the storage capacity of each vitamin)

25
Q

What is steatorrhea?

A

Fat in the feces

26
Q

What intestinal diseases may cause impaired absorption of folate?

A

Sprue and celiac disease

27
Q

Is folate heat labile or heat stable?

A

Labile

28
Q

Is B12 heat labile or heat stable?

A

Stable

29
Q

Binding carrier for B12 in the stomach?

A

Haptocorrin

30
Q

Binding carrier for B12 in the small intestine?

A

Intrinsic factor

31
Q

Binding carrier for B12 in enterocyte?

A

Transcobalamin

32
Q

What autoimmune disease is the result of lack of intrinsic factor?

A

Pernicious anemia

33
Q

What are two examples of competition for B12?

A

Fish tapeworm, and blind loops (portions of the intestine that are stenotic as a result of surgery and have an overgrowth of competing intestinal bacteria)

34
Q

What disease may cause a failure to separate B12 from haptocorrin due to the lack of gastric acidity or trypsin?

A

Chronic pancreatic disease

35
Q

What does H. pylori do to cause a lack of intrinsic factor?

A

Destroys parietal cells of the stomach and intestines

36
Q

What is achlorhydria?

A

A lack of hydrochloric acid in the gastric digestive fluids

37
Q

What are the most indicative clues of megaloblastic anemia from a blood smear?

A

Dacrocytes, oval macrocytes, hypersegmented neutophils and possibly Howell-Jolly bodies, occasional pronormoblasts

38
Q

Why is the MCHC usually within normal range for megaloblastic anemia?

A

Because the hgb production is not affected

39
Q

Why is the MCV usually high for megaloblastic anemia?

A

Because of the increase volume of the cells

40
Q

Is the retic count elevated for megaloblastic anemia?

A

No

41
Q

Is the RDW elevated for megaloblastic anemia?

A

Yes

42
Q

What happens to the H and H levels in megaloblastic anemia?

A

They are decreased

43
Q

When is a bone marrow exam done for megaloblastic anemia?

A

To confirm hypercellular marrow when there is pancytopenia in the blood

44
Q

What will you see in bone marrow exam for a patient with megaloblasic anemia?

A

Large banded neutrophils, many large immature blast cells and nuclear-cytoplasm asynchrony

45
Q

What happens to methylmalonic acid levels when B12 levels decrease? Why does this happen?

A

It increases due to the fact that B12 is a cofactor needed to convert methylmalonyl CoA to succinyl CoA (some of the accumulated methylmonyl CoA is hydrolyzed to methylmalonic acid)

46
Q

What happens to the levels of homocysteine when folate or B12 are decreased?

A

It is increased

47
Q

What sort of test is done to diagnose pernicious anemia?

A

Antibody assay to detect the development of antibodies to intrinsic and parietal cells

48
Q

When is a stool analysis done for B12 deficiency?

A

To detect the presence of D. latum (hookworm)

49
Q

What are the nonmegaloblastic macrocytic anemias?

A

Liver disease, chronic alcoholism and bone marrow failure (or aplastic anemia)

50
Q

Are retics increased in a patient with nonmegaloblastic macrocytic anemia?

A

Yes!

51
Q

Do you see hypersegmented neutrophils and oval macrocytes in nonmegaloblastic macrocytic anemia?

A

No

MLS Hematology (2 decks)

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